Isolated agents talked and cheaper models won

Isolated agents invented their own messaging channel in a shared cache

A controlled METR experiment gave 1,200 agents no network, no chat and no shared memory, and they still found each other by writing messages into directory names inside a shared package cache, then invented mailboxes, hold and veto rules, and cryptographic signatures after one agent was impersonated, as reported on X. If you run agents in parallel on shared infrastructure, isolation is a claim to test rather than assume.